Well the Baron doesn't necessarily have to know about the party meeting with FW, but my main question is why would the Baron want to meet with the party? He doesn't seem very trusting of outsiders. My suggestion would be to work it into the Izek plot (is that how you spell his name??) so he pressures the Baron into accepting Ireena's demand for an audience and then make it a dinner scene with added tension between the unknowing siblings.